Reland "In-object double fields unboxing (for 64-bit only)."

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 840 matching lines @@
 
 
 class AccessorPair;
 class AllocationSite;
 class AllocationSiteCreationContext;
 class AllocationSiteUsageContext;
 class DictionaryElementsAccessor;
 class ElementsAccessor;
 class FixedArrayBase;
 class GlobalObject;
+class LayoutDescriptor;
+class LookupIterator;
 class ObjectVisitor;
-class LookupIterator;
 class StringStream;
 class TypeFeedbackVector;
 class WeakCell;
 // We cannot just say "class HeapType;" if it is created from a template... =8-?
 template<class> class TypeImpl;
 struct HeapTypeConfig;
 typedef TypeImpl<HeapTypeConfig> HeapType;
 
 
 // A template-ized version of the IsXXX functions.
@@ skipping 54 matching lines @@
   V(FixedFloat32Array)             \
   V(FixedFloat64Array)             \
   V(FixedUint8ClampedArray)        \
   V(ByteArray)                     \
   V(FreeSpace)                     \
   V(JSReceiver)                    \
   V(JSObject)                      \
   V(JSContextExtensionObject)      \
   V(JSGeneratorObject)             \
   V(JSModule)                      \
+  V(LayoutDescriptor)              \
   V(Map)                           \
   V(DescriptorArray)               \
   V(TransitionArray)               \
   V(TypeFeedbackVector)            \
   V(DeoptimizationInputData)       \
   V(DeoptimizationOutputData)      \
   V(DependentCode)                 \
   V(FixedArray)                    \
   V(FixedDoubleArray)              \
   V(ConstantPoolArray)             \
@@ skipping 1109 matching lines @@
 
   // Convert and update the elements backing store to be a
   // SeededNumberDictionary dictionary.  Returns the backing after conversion.
   static Handle<SeededNumberDictionary> NormalizeElements(
       Handle<JSObject> object);
 
   // Transform slow named properties to fast variants.
   static void MigrateSlowToFast(Handle<JSObject> object,
                                 int unused_property_fields, const char* reason);
 
+  inline bool IsUnboxedDoubleField(FieldIndex index);
+
   // Access fast-case object properties at index.
   static Handle<Object> FastPropertyAt(Handle<JSObject> object,
                                        Representation representation,
                                        FieldIndex index);
   inline Object* RawFastPropertyAt(FieldIndex index);
+  inline double RawFastDoublePropertyAt(FieldIndex index);
+
   inline void FastPropertyAtPut(FieldIndex index, Object* value);
+  inline void RawFastPropertyAtPut(FieldIndex index, Object* value);
+  inline void RawFastDoublePropertyAtPut(FieldIndex index, double value);
   void WriteToField(int descriptor, Object* value);
 
   // Access to in object properties.
   inline int GetInObjectPropertyOffset(int index);
   inline Object* InObjectPropertyAt(int index);
   inline Object* InObjectPropertyAtPut(int index,
                                        Object* value,
                                        WriteBarrierMode mode
                                        = UPDATE_WRITE_BARRIER);
 
@@ skipping 1043 matching lines @@
   }
 
   static int ToValueIndex(int descriptor_number) {
     return kFirstIndex +
            (descriptor_number * kDescriptorSize) +
            kDescriptorValue;
   }
 
   // Transfer a complete descriptor from the src descriptor array to this
   // descriptor array.
-  void CopyFrom(int index,
-                DescriptorArray* src,
-                const WhitenessWitness&);
+  void CopyFrom(int index, DescriptorArray* src, const WhitenessWitness&);
 
   inline void Set(int descriptor_number,
                   Descriptor* desc,
                   const WhitenessWitness&);
 
   // Swap first and second descriptor.
   inline void SwapSortedKeys(int first, int second);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(DescriptorArray);
 };
@@ skipping 1621 matching lines @@
                                           elementType scalar);                \
     static inline elementType defaultValue();                                 \
   };                                                                          \
                                                                               \
   typedef FixedTypedArray<Type##ArrayTraits> Fixed##Type##Array;
 
 TYPED_ARRAYS(FIXED_TYPED_ARRAY_TRAITS)
 
 #undef FIXED_TYPED_ARRAY_TRAITS
 
+
 // DeoptimizationInputData is a fixed array used to hold the deoptimization
 // data for code generated by the Hydrogen/Lithium compiler.  It also
 // contains information about functions that were inlined.  If N different
 // functions were inlined then first N elements of the literal array will
 // contain these functions.
 //
 // It can be empty.
 class DeoptimizationInputData: public FixedArray {
  public:
   // Layout description.  Indices in the array.
@@ skipping 1077 matching lines @@
   inline bool has_code_cache();
 
   // [prototype]: implicit prototype object.
   DECL_ACCESSORS(prototype, Object)
 
   // [constructor]: points back to the function responsible for this map.
   DECL_ACCESSORS(constructor, Object)
 
   // [instance descriptors]: describes the object.
   DECL_ACCESSORS(instance_descriptors, DescriptorArray)
-  inline void InitializeDescriptors(DescriptorArray* descriptors);
+
+  // [layout descriptor]: describes the object layout.
+  DECL_ACCESSORS(layout_descriptor, LayoutDescriptor)
+  // |layout descriptor| accessor which can be used from GC.
+  inline LayoutDescriptor* layout_descriptor_gc_safe();
+
+  // |layout descriptor| accessor that is safe to call even when
+  // FLAG_unbox_double_fields is disabled (in this case Map does not contain
+  // |layout_descriptor| field at all).
+  inline LayoutDescriptor* GetLayoutDescriptor();
+
+  inline void UpdateDescriptors(DescriptorArray* descriptors,
+                                LayoutDescriptor* layout_descriptor);
+  inline void InitializeDescriptors(DescriptorArray* descriptors,
+                                    LayoutDescriptor* layout_descriptor);
 
   // [stub cache]: contains stubs compiled for this map.
   DECL_ACCESSORS(code_cache, Object)
 
   // [dependent code]: list of optimized codes that weakly embed this map.
   DECL_ACCESSORS(dependent_code, DependentCode)
 
   // [back pointer]: points back to the parent map from which a transition
   // leads to this map. The field overlaps with prototype transitions and the
   // back pointer will be moved into the prototype transitions array if
@@ skipping 309 matching lines @@
   static const int kPrototypeOffset = kBitField3Offset + kPointerSize;
   static const int kConstructorOffset = kPrototypeOffset + kPointerSize;
   // Storage for the transition array is overloaded to directly contain a back
   // pointer if unused. When the map has transitions, the back pointer is
   // transferred to the transition array and accessed through an extra
   // indirection.
   static const int kTransitionsOrBackPointerOffset =
       kConstructorOffset + kPointerSize;
   static const int kDescriptorsOffset =
       kTransitionsOrBackPointerOffset + kPointerSize;
+#if V8_DOUBLE_FIELDS_UNBOXING
+  static const int kLayoutDecriptorOffset = kDescriptorsOffset + kPointerSize;
+  static const int kCodeCacheOffset = kLayoutDecriptorOffset + kPointerSize;
+#else
+  static const int kLayoutDecriptorOffset = 1;  // Must not be ever accessed.
   static const int kCodeCacheOffset = kDescriptorsOffset + kPointerSize;
+#endif
   static const int kDependentCodeOffset = kCodeCacheOffset + kPointerSize;
   static const int kSize = kDependentCodeOffset + kPointerSize;
 
   // Layout of pointer fields. Heap iteration code relies on them
   // being continuously allocated.
   static const int kPointerFieldsBeginOffset = Map::kPrototypeOffset;
   static const int kPointerFieldsEndOffset = kSize;
 
   // Byte offsets within kInstanceSizesOffset.
   static const int kInstanceSizeOffset = kInstanceSizesOffset + 0;
@@ skipping 57 matching lines @@
   typedef FixedBodyDescriptor<kPointerFieldsBeginOffset,
                               kPointerFieldsEndOffset,
                               kSize> BodyDescriptor;
 
   // Compares this map to another to see if they describe equivalent objects.
   // If |mode| is set to CLEAR_INOBJECT_PROPERTIES, |other| is treated as if
   // it had exactly zero inobject properties.
   // The "shared" flags of both this map and |other| are ignored.
   bool EquivalentToForNormalization(Map* other, PropertyNormalizationMode mode);
 
+  // Returns true if given field is unboxed double.
+  inline bool IsUnboxedDoubleField(FieldIndex index);
+
 #if TRACE_MAPS
   static void TraceTransition(const char* what, Map* from, Map* to, Name* name);
   static void TraceAllTransitions(Map* map);
 #endif
 
+  static inline Handle<Map> CopyInstallDescriptorsForTesting(
+      Handle<Map> map, int new_descriptor, Handle<DescriptorArray> descriptors,
+      Handle<LayoutDescriptor> layout_descriptor);
+
  private:
   static void ConnectElementsTransition(Handle<Map> parent, Handle<Map> child);
   static void ConnectTransition(Handle<Map> parent, Handle<Map> child,
                                 Handle<Name> name, SimpleTransitionFlag flag);
 
   bool EquivalentToForTransition(Map* other);
   static Handle<Map> RawCopy(Handle<Map> map, int instance_size);
   static Handle<Map> ShareDescriptor(Handle<Map> map,
                                      Handle<DescriptorArray> descriptors,
                                      Descriptor* descriptor);
   static Handle<Map> CopyInstallDescriptors(
-      Handle<Map> map,
-      int new_descriptor,
-      Handle<DescriptorArray> descriptors);
+      Handle<Map> map, int new_descriptor, Handle<DescriptorArray> descriptors,
+      Handle<LayoutDescriptor> layout_descriptor);
   static Handle<Map> CopyAddDescriptor(Handle<Map> map,
                                        Descriptor* descriptor,
                                        TransitionFlag flag);
-  static Handle<Map> CopyReplaceDescriptors(Handle<Map> map,
-                                            Handle<DescriptorArray> descriptors,
-                                            TransitionFlag flag,
-                                            MaybeHandle<Name> maybe_name,
-                                            const char* reason,
-                                            SimpleTransitionFlag simple_flag);
+  static Handle<Map> CopyReplaceDescriptors(
+      Handle<Map> map, Handle<DescriptorArray> descriptors,
+      Handle<LayoutDescriptor> layout_descriptor, TransitionFlag flag,
+      MaybeHandle<Name> maybe_name, const char* reason,
+      SimpleTransitionFlag simple_flag);
+
   static Handle<Map> CopyReplaceDescriptor(Handle<Map> map,
                                            Handle<DescriptorArray> descriptors,
                                            Descriptor* descriptor,
                                            int index,
                                            TransitionFlag flag);
 
   static Handle<Map> CopyNormalized(Handle<Map> map,
                                     PropertyNormalizationMode mode);
 
   // Fires when the layout of an object with a leaf map changes.
   // This includes adding transitions to the leaf map or changing
   // the descriptor array.
   inline void NotifyLeafMapLayoutChange();
 
   static Handle<Map> TransitionElementsToSlow(Handle<Map> object,
                                               ElementsKind to_kind);
 
   // Zaps the contents of backing data structures. Note that the
   // heap verifier (i.e. VerifyMarkingVisitor) relies on zapping of objects
   // holding weak references when incremental marking is used, because it also
   // iterates over objects that are otherwise unreachable.
   // In general we only want to call these functions in release mode when
   // heap verification is turned on.
   void ZapPrototypeTransitions();
   void ZapTransitions();
 
   void DeprecateTransitionTree();
   void DeprecateTarget(PropertyType type, Name* key,
                        PropertyAttributes attributes,
-                       DescriptorArray* new_descriptors);
+                       DescriptorArray* new_descriptors,
+                       LayoutDescriptor* new_layout_descriptor);
 
   Map* FindLastMatchMap(int verbatim, int length, DescriptorArray* descriptors);
 
   void UpdateFieldType(int descriptor_number, Handle<Name> name,
                        Handle<HeapType> new_type);
 
   void PrintGeneralization(FILE* file,
                            const char* reason,
                            int modify_index,
                            int split,
@@ skipping 4585 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_